First, Carolyn Sandell’s home near Caldwell lost electricity for more than 13 hours, then her bed started moving back and forth.

The two events weren’t connected, but they left her shaking nonetheless.

After the power to her home and about 5,000 other Wheatland Electric customers was restored at 3:30 a.m. Monday, the area was rocked at 9:10 a.m. by an earthquake with a magnitude of 3.8, according to the U.S. Geological Survey in Golden, Colo.

“That’s enough to knock things off the wall,” said Paul Caruso, a USGS geophysicist.

Or enough to move a bed.

Sandell was sitting on her bed talking on the phone to her daughter, who works in Caldwell, when her daughter exclaimed, “What’s that?”

Before Sandell could reply, her bed moved about 6 inches from side to side – not once but several times.

“Enough to make you panic,” she said. “It scared me.”

She could hear people yelling in the background at the office where her daughter worked.

The quake’s magnitude was originally pegged by USGS at 4.2. It was later downgraded based on additional information.

The epicenter was 11 miles northwest of Caldwell, a town on the Oklahoma-Kansas state line in Sumner County, according to USGS data. That’s about a mile east of the Harper County line.

Frank Smith, who lives in southeast Harper County, said he also felt it – but only for a split second.

“I thought it was an explosion at first,” he said.

As of late afternoon, the USGS office had received 142 reports of strong to light tremors from 66 ZIP codes stretching from almost 40 miles southwest of Haysville to south of Edmond, Okla.

Small earthquakes in southern Kansas have become more common, with 13 recorded over the past two years in Sumner, Harper and Barber counties, according to the Kansas Geological Survey.

That area also has been the site of increased oil and gas drilling since January 2011. In a six-county area along the Kansas-Oklahoma state line – Comanche, Barber, Harper, Sumner, Cowley and Chautauqua counties – 271 horizontal wells have reported production through July, according to KGS officials.

Hydraulic fracturing comes in the final stages of the horizontal drilling.

Lynn Watney, a geologist who monitors the oil industry for KGS, said it’s unknown whether such man-made events as drilling or fracturing have caused the uptick in quakes or whether they came from a natural occurrence.

“We’re still looking at it more closely,” he said. “We want to make sure (drilling) doesn’t create any earthquake activity.

“But right now, we don’t know what is making this happen.”

One of the issues for measuring earthquakes in Kansas is that the USGS has only two monitoring stations in the state – one near Manhattan and the other southwest of Hays near Cedar Bluff State Park. Oklahoma has far more USGS stations.

To help get a better handle on tracking earthquake activity in the area, a monitor will be placed at a drilling site near Wellington in about a year, Watney said. The site is for a project to test the use of injecting carbon dioxide into wells to move the oil.

As for the power outage that started the day for Sandell and others, a fire of unknown origin knocked out a transmission structure operated by Westar Energy in southwest Sedgwick County just west of Viola, Westar spokesman Leonard Allen said

Wheatland is a co-op that buys its electricity from Westar, which is why its customers in Kingman, Harper and Sumner counties were affected. Two 40-foot poles for the structure that carried a 138,000-volt transmission line had to be replaced before power could be restored, Allen said.